The conventional stacked semiconductor package has a bottom package and a top package. The bottom package comprises a substrate, a solder mask layer, a die and a molding compound. The substrate has an upper surface, a plurality of first pads and a plurality of second pads. The second pads are disposed on the upper surface. The solder mask layer is disposed on the upper surface, and has a plurality of openings exposing the first pads and the second pads. The die is attached to the solder mask layer by an adhesive layer, and electrically connected to the first pads by a plurality of wires. The molding compound encapsulates part of the solder mask layer, the wires and the die.
The top package comprises a plurality of solder balls. The solder balls contact the second pads, so that the top package is electrically connected to the bottom package.
One disadvantage of the conventional stacked semiconductor package is that as the distance between neighboring solder balls decreases, the diameter of each solder ball must also decrease. Therefore, when the thickness of the die and/or molding compound cannot be sufficiently thinned to accommodate the reduced diameter solder balls, the top package may not properly connect electrically to the bottom package.
Therefore, it would be advantageous to provide stacked semiconductor packages and methods of making semiconductor packages to address the above-mentioned problems.